Russ,Where exactly in the HT1632C datasheet do you see those currents? Is it for pins OSC and SYNC? If so, those are not used for driving the 3216 display. You only need to use the pins WR, CS and DATA (as input only, if you are using the existing library). I could not find any spec saying WR and CS take 20mA.

I guess to drive the IO i could put a mini 4port Buffer on each LED board and then use 1 buffer on my control board.The reason i want it layed out like this is, that i can have a quite nice little bus loom to wiring it all together that is not to complex

to display information, i will first select one of the chip select lines. which will intern select 4 boards(8chips) and then write data to all 8 chips at once using my 8 data lines. i do this 8 times thats all 64 chips updated!! using only 12 IO lines!!!

DATA is input/output, similar to GPIOs on ATmega328, for example. The datasheet for ATmega328 says DC current per I/O pin is 40mA.Does that mean that the GPIO pin takes 40mA when used as input? I highly doubt it.Similarly, the DATA pin on HT1632C, when used as output, can typically source 20mA.As I said, the library only uses DATA as input.